1. Field of the Invention
The present invention relates to a fuel supply device for a direct injection internal combustion engine and, more particular, to a fuel supply device for supplying fuel to a direct injection internal combustion engine in which a layout of a high-pressure fuel pump is improved.
2. Description of Related Art
In a front engine-front drive (FF) type of vehicle, an engine is installed in a front engine compartment with a row of cylinders in a transverse direction of the vehicle. As known from, for instance, Japanese Unexamined Patent Application No. 8-312502, in the case where the front engine-front drive type of vehicle equipped with a direct injection type of internal combustion engine in which fuel is sprayed directly into cylinders, a fuel supply device includes fuel injectors and a high-pressure fuel pump which is used to pressurize fuel and force it into a fuel delivery pipe for distributing fuel to the fuel injectors for stable fuel supply into cylinders through the fuel injectors overcoming high pressure in the cylinders.
Typically, a camshaft or an extension of the camshaft extending beyond an engine in a transverse direction drives a high-pressure fuel pump. Fuel is pressurized by, for example, reciprocating motion of a rod of the high-pressure fuel pump, which is caused by rotation of a cam secured to the camshaft. Because the front engine-front drive type of vehicle is equipped with an internal combustion engine with a row of cylinders directed in a transverse direction of the vehicle and, as a matter of course, the camshaft extends in the transverse direction, the high-pressure fuel pump is located laterally adjacent to the top of the transverse engine.
As schematically shown as one of general arrangements of intake and exhaust systems in FIG. 9, an intake system P2 is located behind a transverse direct injection engine P10 and an exhaust system P3 is located in front of the engine. Further, as schematically shown as another general arrangement of intake and exhaust systems in FIG. 10, an intake system P2 is located in front of engine P10 and an exhaust system P3 is located behind the engine. The latter arrangement makes it possible to have the exhaust system P3 shortened in exhaust gas path length for the purpose of quickly raising a temperature of a catalytic converter in the exhaust system P3 and accelerating activation of the catalyst which is quite notable in light of measures to meet the recent exhaust gas regulations.
In both arrangements, a high-pressure fuel pump P50 is located laterally adjacent to rear part of the top of the transverse engine so as to avoid mechanical interference against a front hood Pz that is inclined forward down. A camshaft extending from rear top portion of the engine body P10 drives the high-pressure fuel pump P50. Specifically, the high-pressure fuel pump P50 is driven by an intake camshaft P14 in the case where the intake system P2 is located behind the engine P2 as shown in FIG. 9, or the high-pressure fuel pump is driven by an exhaust camshaft P15 in the case where the exhaust system P3 is located behind the engine body P10 as shown in FIG. 10.
There is provided a distance between the high-pressure fuel pump P50 and a dash panel Pg when disposing the high-pressure fuel pump P50 a little to the rear of the engine P10 shorter than that when disposing the high-pressure fuel pump P50 a little to the front of the engine body P10 and driving it by a camshaft extending along froward top portion of the engine body P10. The shorter distance between the high-pressure fuel pump P50 and a dash panel Pg provides an increase in probability of damaging the high-pressure fuel pump P50 due to a hit against the dash panel Pg which is caused by rearward movement of the engine body P10 upon an occurrence of a frontal crash of the vehicle. In particular, differently from the arrangement in which the engine body P10 with the intake system P2 located behind the engine and the exhaust system P3 located in front of the engine as shown in FIG. 9, a surge tank P22 is not located between the high-pressure fuel pump P50 and the dash panel Pg in the arrangement in which the engine body P10 with the intake system P2 located in front of the engine and the exhaust system P3 located behind the engine as shown in FIG. 10. Accordingly, the high-pressure fuel pump P50 and the dash panel Pg stand face to face directly with each other, so that the high-pressure fuel pump P50 is apt to easily hit against the dash panel Pg when the engine moves backward. This arrangement is undesirable for structural safety.
It is an object of the present invention to provide a fuel supply device having a compact arrangement which prevents a high-pressure fuel pump from mechanically interfering with a hood of an engine compartment and provides a large distance between the high-pressure fuel pump and a structural member such as a dash panel behind the high-pressure fuel pump in consideration with prevention of an impact possibly applied to the high-pressure fuel pump upon occurrence of a frontal crash of the vehicle.
The foregoing object of the present invention is accomplished by providing a fuel supply device for a direct injection internal combustion engine with a row of cylinders directed in a transverse direction of a vehicle body for supplying fuel to fuel injectors adapted to spray fuel directly into cylinders, which comprises at least two camshafts extending in parallel to each other along the engine in the transverse direction and a high-pressure fuel pump for pressurizing said fuel and forcing it into the fuel injector. The high-pressure fuel pump is located laterally adjacent to front or rear part of the engine so as to be driven by one of the two camshafts located along the part of the engine and is installed in a position inclined forward or rearward.
According to the fuel supply device, in an arrangement wherein the high-pressure fuel pump E50 is located laterally adjacent to forward part of the engine body E10 and is driven by one of the two camshaft E14 which is located along the forward part of the engine body E10 as schematically shown in FIG. 7, because the high-pressure fuel pump P50 is not in an upright position but is inclined rearward, the high-pressure fuel pump E50 shifts rearward in position from the upright position, so that the high-pressure fuel pump E50 is prevented from mechanically interfering with the hood of engine compartment Ez though it is located in a forward position with respect to the engine body E10. Additionally, the high-pressure fuel pump E50 is intentionally positioned forward with respect to the engine body E10 in the engine compartment Ex, so that there is provided a long distance between the high-pressure fuel pump E10 and the dash panel Eg behind the high-pressure fuel pump E50, thereby lowering energy of an impact applied to the high-pressure fuel pump E50 by the dash panel Eg when the engine body E10 moves rearward upon an occurrence of frontal crash of the vehicle.
On the other hand, in an arrangement wherein the high-pressure fuel pump E50 is located laterally adjacent to rearward part of the engine body E10 and is driven by one of the two camshaft E15 which is located along the rearward part of the engine body E10 as schematically shown in FIG. 8, because the high-pressure fuel pump P50 is not in an upright position but is inclined forward, the high-pressure fuel pump E50 shifts forward in position from the upright position, so that there is provided a long distance between the high-pressure fuel pump E10 and the dash panel Eg behind the high-pressure fuel pump E50 even though it is located in a rearward position with respect to the engine body E10 thereby lowering energy of an impact applied to the high-pressure fuel pump E50 by the dash panel Eg when the engine body E10 moves rearward upon an occurrence of frontal crash of the vehicle. Additionally, the high-pressure fuel pump E50 is intentionally positioned rearward with respect to the engine body E10 in the engine compartment Ex, so that the high-pressure fuel pump E50 is prevented from mechanically interfering with the hood Ez of the engine compartment Ez.
If inclining forward the high-pressure fuel pump E50 located in a forward position, the high-pressure fuel pump E50 shifts into a more forward position from the originally intended upright position. This arrangement is hard to prevent the high-pressure fuel pump E50 from mechanically interfering with the hood Ez. Similarly, if inclining rearward the high-pressure fuel pump E50 located in a rearward position, the high-pressure fuel pump E50 shifts into a more rearward position from the originally intended upright position. This arrangement is hard to prevent the high-pressure fuel pump E50 from mechanically interfering with the hood Ez.
The fuel supply device shown in FIG. 7 or 8 is shown by way of example in which an engine is equipped with the intake system E2 disposed in front of the engine body E10 and the exhaust system E3 disposed behind the engine body E10 like the engine P10 shown as prior art in FIG. 10. In this arrangement, the high-pressure fuel pump E50 is driven by an intake camshaft E14 as shown in FIG. 7 or by an exhaust camshaft E15 as shown in FIG. 8. However, the fuel supply device of the present invention can be installed to such an engine P10 equipped with the intake system P2 disposed behind the engine body P10 and the exhaust system P3 located in front of the engine body P10 as shown as prior art in FIG. 9. This arrangement, in which the high-pressure fuel pump E50 is driven by an exhaust camshaft E15 as shown in FIG. 7 or by an intake camshaft E15 as shown in FIG. 8, provides the same effects as the former arrangement.
The fuel supply device includes the intake system and fuel injector may be installed to the front of the engine body, and the high-pressure fuel pump is located laterally adjacent to the forward part of the engine body so as to be driven by the intake camshaft and inclined rearward.
According to the fuel supply device, as shown in FIG. 7, in the arrangement in which the engine E10 is equipped with the exhaust system E3 disposed behind the engine body E10 for the purpose of accelerating activation of a catalytic converter device and the intake system E2 and a fuel injector E60, or a fuel delivery pipe E60 for delivering fuel to the fuel injector E60, disposed on the front side of the engine body E10, the high-pressure fuel pump E50 is driven not by the exhaust camshaft E15 located at the rear part of the engine body E10 but by the intake camshaft E14 located at the front part of the engine body E10, so as to make it possible to use various pipes Em and En made short in length between the high-pressure fuel pump E50 and the fuel injector E60 or the fuel delivery pipe E60 and, in consequence, to provide a reduction in pumping loss of the high-pressure fuel pump E50. The high-pressure fuel pump E50 has a fuel inlet port through which fuel is introduced in and a fuel discharge port through which pressurized fuel is discharged. Either one of the fuel inlet port and fuel discharge port may be located at the rear bottom of the high-pressure fuel pump in the inclined position. Further, a fuel return pipe E46 through which excessive low pressure fuel returns into the high-pressure fuel pump E50 may be connected to a back wall Ep facing rearward up of the high-pressure fuel pump inclined rearward.
According to the fuel supply device, as shown in FIG. 7, one of the fuel pipes, for example a pressurized fuel supply pipe E45, is connected to the rear bottom Eo of the high-pressure fuel pump E50 inclined rearward, so that the joint structure between the high-pressure fuel pump E50 and the pressurized fuel supply pipe E45 is directed toward the inside of the vehicle body. This arrangement significantly reduces an occurrence of such a trouble as the joint is damaged or breaking away due to an impact from the front or the top of the vehicle body.
In the case where the fuel discharge port to which the pressurized fuel supply pipe E45 is connected to supply pressurized fuel to the fuel injector E60 is located at the bottom of the high-pressure fuel pump E50 inclined rearward, the pressurized fuel supply pipe E45 and the joint between the high-pressure fuel pump E50 and the pressurized fuel supply pipe E45 are directed toward the inside of the vehicle body, so that the joint and the pressurized fuel supply pipe E45 are prevented from being damaged or breaking away from the high-pressure fuel pump E50 due to an impact from the front or the top of the vehicle body. In this arrangement, while a metal pipe is preferably used for the pressurized fuel supply pipe E45, a plastic pipe may be used for the fuel return pipe E46.
According to this arrangement in which a metal pipe and a plastic pipe are used for the pressurized fuel supply pipe E45 and the fuel return pipe E46, respectively, the pressurized fuel supply metal pipe E45 connected to the rear bottom Eo of the high-pressure fuel pump E50 has relatively low elasticity and lacks in flexibility and, on the other hand, the fuel return plastic pipe E46 connected to the back wall Ep facing rearward up of the high-pressure fuel pump E50 has relatively high elasticity and is flexible. Therefore, the joint between the high-pressure fuel pump E50 and the pressurized fuel supply metal pipe E45 through which highly pressurized fuel passes is directed toward the inside of the vehicle body, so that the joint and the pressurized fuel supply metal pipe E45 are prevented from being damaged or breaking away from the high-pressure fuel pump E50 due to an impact from the front or the top of the vehicle body, with increased reliability.